Elongate storage tanks on trucks for holding liquids such as water often have an elliptical or circular cross section. For uses such as fire fighting, the tanks are sometimes made of plastic, for example, polypropylene. Such storage tanks are typically supported by a cradle type structure that is mounted to the frame or chassis of the truck. The drawback of the typical cradle structure is that the storage tank merely rests upon the cradle structure, and as a result, can lift off the cradle structure when the truck goes over bumps or around sharp corners.
The present invention is directed to a mounting assembly for firmly securing a storage tank to the chassis of a vehicle in a manner which prevents lifting of the tank during normal usage. The mounting assembly includes a pair of longitudinal support structures for securing to a bottom wall of the storage tank, a cross bracket for mounting between the longitudinal support structures, a sub-frame for supporting the longitudinal support structures and the cross bracket, and a bracket assembly for securing the cross bracket to the sub-frame to prevent the tank from lifting upwardly relative to the sub-frame.
In preferred embodiments, the storage tank and longitudinal support structures are formed of plastic, and the cross bracket, sub-frame and bracket assembly are formed of metal. Typically, the storage tank has a curved bottom wall. The longitudinal support structures are generally channel shaped. Internal reinforcement members are included for extending along the inside of the longitudinal support structures to clamp the cross bracket to the longitudinal support structures and distribute stress. The reinforcement members are preferably metallic angle brackets. The sub-frame includes two longitudinal members connected together by a connecting structure. The bracket assembly preferably includes a series of U-shaped brackets for securing the connecting structure of the sub-frame to the cross bracket. The sub-frame is mounted to the chassis rails of the vehicle and isolator pads are included for positioning therebetween to isolate the sub-frame from the chassis rails. In addition, resilient pads are provided for positioning between the longitudinal support structures and the sub-frame.
The present invention mounting assembly allows a plastic storage tank having a curved bottom wall to be securely mounted to the chassis of a vehicle in a relatively simple and inexpensive fashion so that the tank does not lift relative to the chassis during normal operation of the vehicle, for example, going over bumps and around corners. This is accomplished without overstressing the plastic components of the tank.